A known tire changer apparatus for removing large tires from drop center wheel rims for tractors and other off-road vehicles utilizes an upright hydraulic cylinder for pushing the tire off the rim after the beads at the side opposite the cylinder are manipulated into the drop center of the wheel rim, as in U.S. Pat. No. 3,612,140.
The portion of the tire casing so pushed does not move directly upward, but in an arc first slightly backwards and then substantially forward. Using a linear actuator fixed in a vertical position, the casing being removed exerts a resisting force on the actuator shoe which has a perpendicular component. Due to dimensional requirements, it is usually necessary to use telescoping hydraulic cylinders for this purpose, which are more easily damaged by perpendicular acting forces than more conventional cylinders.
Since the actuator rod of a hydraulic cylinder is free to rotate, the shoe atop the actuator rod may become angularly displaced, then being in improper position for retraction.